This invention relates to a novel composite material composed of non-oxide ceramics and metal.
Ceramics, especially of the non-oxide type, have various desirable properties such as high heat resistance, wear resistance and chemical resistance. Ceramics of the non-oxide type, however, have a number of drawbacks as being brittle and low in impact strength, therefore for use as a structural material, it is usual to use a composite material composed of ceramics and a metal instead of using ceramics alone.
Various kinds of such composite materials have hitherto been developed. They include a composite material composed of non-oxide type ceramics and iron or an iron alloy. Although a composite material containing iron or an alloy thereof is expected to be useful for a wide range of application, no such material of satisfactory properties has so far been obtained. In order to manufacture such composite material, it has hitherto been usual to bond non-oxide type ceramics directly to iron or an alloy thereof or to dispose an intermediate layer by which the ceramic and iron components are bonded to each other. Iron or an alloy thereof, however, has a coefficient of thermal expansion which greatly differs from that of ceramics. If they are bonded to each other directly, they are easily separated from each other or broken when exposed to a thermal shock. This problem has been solved by the provision of an intermediate layer which may be formed from a soft metal, such as aluminum, or a foamed metal, and which undergoes elastic or plastic deformation to mitigate any strain of thermal expansion. A composite material including such an intermediate layer has an improved thermal shock resistance, but an extremely low adhesive strength between ceramics and iron or an alloy thereof.